Wheres the Model in Zend Frameworks MVC?
Don’t get me wrong ZF is my PHP framework of choice however it’s really lacking the Model concept from the MVC design pattern! The Model is where you should be implementing your business logic, data validation for example…
Zend Framework implements interfaces for filtering and validation on it’s Form components. The framework however lacks these interfaces on other components suitable to implement a true MVC design pattern where the validation would occur in the Model.
The interfaces on the Form component aren’t suitable for complex applications where a single model is used by multiple forms in the application. Say you store your email addresses in a single table in your database, but in your application, multiple ‘objects’ have email addresses associated with them… Should u have to setup the email address validation 10 times for each form the field is used in? I don’t think so…
I’m yet to work out the perfect solution to this unfortunately, but some ideas I’ve had are:
- Store you Form Elements in your model classes and add them to your forms in the Controller as required.
- Create you own model class with it’s own validation interfaces.
The second option is what I’ve done in past applications and I’m just about to start my next and decided to see if there is a better solution out there… The best article I’ve found was at techfounder and was proposing the second option as well and had some good examples. And model class approach on jmgtan.. However both still leave a lot to be desired :(
I’d be interested to hear any other ideas, or see any other bookmarks you have!
December 6th, 2008 at 4:42 am
This are great ideas to think about. Yes, we will address the problem of models- probably in 1.9.
You know, we’ve probably not stated this part of our philosophy enough. In the Zend Framework project, we typically don’t address a problem if it has either of the following 2 aspects:
1) It’s already been addressed well in the PHP community, and we don’t see any significant value that we can add over existing solutions by building our own. ZF was designed to work well alongside other application components.
2) We don’t fully understand the problem and are working with the community to see what people generally want and need.
In this case, the second point applies. One might argue that the problem of models is already solved in most- if not all- other MVC frameworks. True, but we’re not convinced that we can’t do it in a more flexible way yet.
The fact is that the M is the hardest thing to abstract in MVC. It is the core of your application and can look very different from application to application.
For example, M could be a DB-backed ActiveRecord. But for many people it’s backed by a RESTful service. Or CouchDB. Or practically an infinite number of other things.
Some people also like to handle forms in the model. Others see them more as a responsibility of the presentation layer. This can also drastically affect where and how validation is performed.
Some people like thick controllers, other people like thin. This won’t affect the view or controller abstractions significantly, but it might affect models a lot.
The issues in the model problem go on and on. The ZF team feels like it has good answers for lots of these problems, but we’re not ready to say that we have all the answers yet.
So, we’ve punted on it and took the widely criticized route of not introducing any model abstraction. In essence, ZF doesn’t tell you what your models are at all; that’s completely up to you. I lot of people see this as an omission- and it is- but hardly a resource-constrained or unintentional omission.
That said, we agree with you that there are benefits to be had from a model formalism, especially around forms. Maybe even around the concept of a resource. Please join us on the mailing lists and/or the IRC channels (#zftalk.dev would be the most appropriate for this discussion) and help us think through models to get to the design that will give us a lot of reuse without loosing all the flexibility.
Thanks for the feedback!
,Wil
December 9th, 2008 at 6:32 pm
Agree the Model is a rather diverse beast, and one I myself have been a little overwhelmed designing one for my own reuse…
For others reading this post I should have mentioned earlier the Zend_Model (http://framework.zend.com/wiki/pages/viewpage.action?pageId=41564) proposal by Jurriën Stutterheim a core contributor from the Zym Framework (http://www.zym-project.com) which coincidently has a Zym_Model (http://code.google.com/p/zym/source/browse) component in the frameworks laboratory similar to the original Zend_Model framework proposal.
As mentioned I’ve started work on a Model component for myself and future projects which I hope will address some of the issues/features raising in the discussion on the Zend_Model proposal (but not all since I have a smaller scope than that of a ‘framework’ component)… I’ll share it once I’ve finished if I’m happy with it – although I’m rarely satisfied with my own work ;)